garysol1 your right onto it... Thats the point of the thread everyone will have a personal preference but there is an ideal. Below 90 odd RPM you muslce fibre recruitment is much higher ie you use way more legs than heart. To be most efficient and maximise output at that RPM your legs will fatigue way before your cardovascular system even gets tired.
Hence the difference in Ulrich to Armstrong. Lance will always have better legs at the end of a race for an explosive attack where its out of the question for Jan who pushes a bigger gear and a lower RPM.
The intersting thing is that most people instinctivly find this ideal cadence on there own, even though most poeple have a preference that suits them